How to export animations to use in an Android app
Probably the easiest solution is to export a Wavefront Obj sequence; This will give you a sequence of files, where each represents the positions of each vertex, at the given time. This format is probably the best, since it's very simple and uses ASCII.

To do this in Blender, after you have your animation ready, go to the Header, then File, the Export and finally Wavefront (.obj). The interface layout will change and show you the File Browser, where you can select the output path and name. Before clicking Export, you need to go to the panel on the left and in the subsection Export OBJ check Animation.